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TL;DR below

My bicycle is an old used Trek hybrid (1994?) that I got a few years back. When replacing the tires recently I discovered that my rear axle was significantly bent (not surprising for a freewheel bicycle), and upon removing the axle and bearings I discovered massive cracks all along the freewheel side of the rear hub. (see photos below)

I'm sure that the hub is toast - but where do I go from here? I could buy a hub and rebuild the wheel, but I am guessing that is a waste of money compared to a new wheel.

Where/how do I look for a replacement rear wheel? Rear dropout spacing seems to be about 138mm, rims are 700c and about 26mm wide. I have a 7-speed freewheel that seems fine, but I am wondering if it makes sense to just get a freehub and a new 7-speed cassette to avoid future bent axles. Currently have all Shimano drivetrain components, not sure what model.

I mostly do road riding and commuting, with occasional light gravel. Brakes are rim cantilever style.

imgur photo album

Thanks so much for the help!

TL;DR: Rear hub cracked - new wheel? How much, where to look?

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    Hard to tell for sure, but the lines in the cup appear to be more "spalling" than cracks. However, if you had a bent axle it's often the case that the hub is deformed as well. And, yes, it's generally more sensible (and probably cheaper) to buy a new wheel, vs getting a new hub (which would require new spokes).
    – Daniel R Hicks
    May 23, 2020 at 19:37
  • For a 1994 bike I would consdier a used wheel, or even a donor bike (which could easily be cheaper than a new wheel).
    – mattnz
    May 24, 2020 at 7:46
  • How stuck are you on originality? I'd look for a cassette-based rear wheel, and either fit a 7 speed cassette with a lot of spacers, or take this opportunity to upsize to more gears - the additional/incremental cost would be a cassette and a shifter.
    – Criggie ♦
    May 24, 2020 at 20:32
  • I'm probably just going to go with a freehub-sytle replacement wheel and a new 7-speed cassette to mount to it with a 4.5mm spacer. Seems like the most reasonable option for my situation, and I am definitely not hung up on originality. I want this bike to work and last until its time for a new bike, not to become a museum of vintage Trek.
    – YesAlexCook
    May 25, 2020 at 1:08

2 Answers 2

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The bearing cup is toast from being ridden with a bent axle. The hub shell does not appear to have structural cracks.

With a new axle you could potentially get some life out of it, but you're probably on the right track with replacement, especially if this is a bike you're riding indefinitely.

With either the freewheel or cassette route, the sort of wheel you'd need are very common repair items that are easy to get from a shop or internet retailer. You need any rim brake 135mm 700c hybrid freewheel rear wheel, or any rim brake 135mm 700c hybrid cassette rear wheel plus a new 7 speed cassette and a 4.5mm cassette spacer.

Replacement hybrid wheels with 7-speed freehubs used to be commonplace and are a little technically superior when applicable due to their wider flange spacing, but aren't made by any large wheel producers I've seen in recent years, in part because those bikes are aging and in part because of the explosion in repair wheel compatibility permutations shops and wheel producers have had to deal with in the last decade. Hence running an 8/9/10 with a spacer has become the norm for replacements.

Given it's bent axle problems that got you here, there's a case to be made for switching to cassette. In almost all cases it makes sense to start out a new chain at the same time, and the potential gotcha then becomes the wear state of your chainrings.

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Honestly I don't see anything wrong with the hub. But if it were me I would pick up a generic replacement hub on eBay for a few bucks if you don't want to start the upgrade spiral.

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  • I didn't get a good picture, but there is also very severe spalling on the cones of both sides of the wheel. There is definitely damage present from riding with a bent axle.
    – YesAlexCook
    May 24, 2020 at 11:13

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